the giveaway was in how he bragged about the way the police basically exonerated him right there, because they were so surprised at how innocent she was. these interviews are meant to discover trauma, not knowledge of naughty things. afaict there are four possible scenarios where a little girl sees and recognizes a penis in an interview.
-haha thats a penis just like (daddy, brother, etc) has
-oh i saw one of those when daddy fell asleep in front of the tv. it was fighting with a big oyster and spit all over it
-mommy has a purple one of those in her sock drawer
-*notably disturbed*
only one of these little girls gave a red-flag response.
also, there is no way in hell that the police would even hint at exoneration. even if they knew in their heart of hearts that he didn't do it, they would never had declared him innocent